<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8" />
		<title>输入框 作业</title>
		<script src="js/main.js" type="text/javascript" charset="utf-8"></script>
	</head>
	<body>
		<input type="text" id="ipt" placeholder="请输入用户名"/>
		<span id="wz"></span>
	</body>
</html>
